当磁浮列车运行速度超过400 km·h^(-1)时,四极子声源对列车远场噪声的影响不容忽视。基于大涡模拟(LES)方法和基尔霍夫-福茨.威廉姆-霍金斯(Kirchhoff-Ffowcs Williams and Hawkings,K-FWH)方程,通过合理构建可穿透积分面,对不同...当磁浮列车运行速度超过400 km·h^(-1)时,四极子声源对列车远场噪声的影响不容忽视。基于大涡模拟(LES)方法和基尔霍夫-福茨.威廉姆-霍金斯(Kirchhoff-Ffowcs Williams and Hawkings,K-FWH)方程,通过合理构建可穿透积分面,对不同速度等级下磁浮列车的偶极子、四极子声源特征进行数值仿真分析。结果表明:尾车流线型区域附面层分离引起的空间扰动是磁浮列车气动发声的根源;列车偶极子声源主要分布在磁浮列车头/尾车无线电终端周围、头/尾车流线型抱轨底部以及尾车流线型鼻尖点区域,四极子声源主要分布在尾流区域;当列车分别以400,500及600 km·h^(-1)3个速度级运行时,四极子声源辐射能量分别为62.4%,63.3%和71.7%,均超过偶极子声源,占据主导地位。展开更多
A bridge function approximation is proposed for a single-component fluid consisting of penetrable sphere interacting via a potential that remains finite and constant for center-center distance smaller than the particl...A bridge function approximation is proposed for a single-component fluid consisting of penetrable sphere interacting via a potential that remains finite and constant for center-center distance smaller than the particle diameter and is zero otherwise. The radial distribution function from the Ornstein-Zernike integral equation combined with the present bridge function approximation is in satisfactory agreement with the corresponding simulation data for all of the investigated state points. The presently calculated excess Helmholtz free energy respectively based on virial route and compressibility route is highly self-consistent, and is in very good agreement with simulational results for the case of low temperatures. The present bridge function approximation, combined with the bridge density functional approximation, can reproduce very accurately density profiles of the penetrable sphere fluid confined in a hard spherical cavity for all the cases where simulational results are available.展开更多
文摘当磁浮列车运行速度超过400 km·h^(-1)时,四极子声源对列车远场噪声的影响不容忽视。基于大涡模拟(LES)方法和基尔霍夫-福茨.威廉姆-霍金斯(Kirchhoff-Ffowcs Williams and Hawkings,K-FWH)方程,通过合理构建可穿透积分面,对不同速度等级下磁浮列车的偶极子、四极子声源特征进行数值仿真分析。结果表明:尾车流线型区域附面层分离引起的空间扰动是磁浮列车气动发声的根源;列车偶极子声源主要分布在磁浮列车头/尾车无线电终端周围、头/尾车流线型抱轨底部以及尾车流线型鼻尖点区域,四极子声源主要分布在尾流区域;当列车分别以400,500及600 km·h^(-1)3个速度级运行时,四极子声源辐射能量分别为62.4%,63.3%和71.7%,均超过偶极子声源,占据主导地位。
基金The project supported by Natural Science Foundation of Education Department of Hunan Province of China under Grant No. 04C711 and National Natural Science Foundation of China under Grant No. 20546004.
文摘A bridge function approximation is proposed for a single-component fluid consisting of penetrable sphere interacting via a potential that remains finite and constant for center-center distance smaller than the particle diameter and is zero otherwise. The radial distribution function from the Ornstein-Zernike integral equation combined with the present bridge function approximation is in satisfactory agreement with the corresponding simulation data for all of the investigated state points. The presently calculated excess Helmholtz free energy respectively based on virial route and compressibility route is highly self-consistent, and is in very good agreement with simulational results for the case of low temperatures. The present bridge function approximation, combined with the bridge density functional approximation, can reproduce very accurately density profiles of the penetrable sphere fluid confined in a hard spherical cavity for all the cases where simulational results are available.
